The invention relates to an ultrasonic applicator comprising an ultrasonic head with transducer element means which transmits ultrasonic signals and receives echo signals.
In the human body the organs which are of interest in terms of an ultrasonic scanning, such as, for example, the kidneys, the thyroid gland, the liver, the heart and, in the case of women, also the female breast, respectively, lie at quite variable depths. In addition, these organs do not always exhibit an optimum position regarding the focus of the scanning ultrasonic beam. This applies in principle to all ultrasonic applicators with direct coupling to the body surface solely by way of a coupling gel. Such applicators are e.g. normal compound scanners, mechanical sector scanners and, in particular, also ultrasonic arrays in random design, such as are described e.g. in the article "Real Time Sonography with the Linear Array Scanner Multison 400" by V. Zurinski and R. Haerten in the publication "Electromedica" 46 (1978), No. 4, on pages 141 through 148. In addition, however, also such ultrasonic applicators are known in which the transducer elements are coupled to the body by way of a water precursory path. However, whereas the apparatus which is prior known from the brochure "VIDOSON 735 SM Ultrasonic Real Time Tomograph with Water Precursory Path DATA E 441" from the year 1979, does not render possible, without special measures, any variation of the distance of the transducer elements from the body surface, within the water precursory path, in the case of the ultrasonic array of U.S. Pat. No. 4,163,394, such a distance variation is possible. The last cited ultrasonic applicator relates specifically to a sector scanner which, on the basis of the curved design of the ultrasonic array, linearly scans in a sector. A displacement installation is provided which renders possible, within the water precursory path, an alteration of the distance between the curved array and the coupling location on the body. The location of the apex of the sector field in the interior of the body can hereby be varied to a certain extent with a simultaneous displacement of the entire sector field. The solution of U.S. Pat. No. 4,163,394 can be, at best, applied only to pure sector scanning, on the one hand. It is also relatively complicated, on the other hand, because an ultrasonic head with transducer elements must be arranged and displaced within a water bath in the housing of the ultrasonic applicator. A solution is desirable which is technically far simpler and, in addition, is also universally applicable to every type of ultrasonic applicator of the type referred to above.